(i) Technical Field
The present invention relates to a color processing apparatus and a computer-readable medium storing a color processing program.
(ii) Related Art
In general, in color management systems (CMYs) or the like, in order to grasp the characteristics of an apparatus that handles color images, a patch set that is a set of multiple colors and measured color values corresponding to the individual colors are necessary. For example, in order to grasp the color output characteristics of an image output apparatus, values corresponding to individual colors included in a patch set are supplied to the image output apparatus. Measured color values corresponding to the individual colors are obtained by measuring colors that have been output. In a case of an image reading apparatus, individual colors included in a patch set are printed and measured to obtain measured color values. A printed material is read by the image reading apparatus, and values corresponding to individual colors that have been output from the image reading apparatus and the measured color values are associated with each other.
The degree of accuracy of the obtained characteristics of an apparatus increases with the number of colors that are prepared as colors to be included in a patch set. However, efforts to measure the colors increase. Furthermore, also when the input/output characteristics of an apparatus is subjected to modeling, thereby obtaining a model, it takes time to configure the model. Thus, the number of colors that are to be included in a patch set is limited.
For example, in a case of an image output apparatus, combinations of values that are obtained at predetermined steps for individual color elements of color materials or display colors which are used in the image output apparatus may be used as colors that are to be included in a patch set. However, the input/output characteristics of an apparatus in each portion of a color space vary. Even when the characteristics of the apparatus are obtained using colors included in a patch set, the apparatus does not necessarily have the same characteristics for the other colors. Thus, a case is supposed, in which a patch set is configured using the above-described combinations of simple values, in which the input/output characteristics of an apparatus is obtained to generate a color conversion model, and in which a color that is to be output from the apparatus is predicted. In such a case, a prediction accuracy, i.e., an error between a color that is output in reality when a certain color is supplied to the apparatus and a predicted value, differs depending on the color. For example, if a color belonging to a color region in which a provided prediction accuracy has not been obtained as the prediction accuracy is included in a patch set, the prediction accuracy in the color region is improved. In contrast, even when a certain color is removed from the patch set, the prediction accuracy does not change much. Accordingly, the prediction accuracy differs depending on which color is to be selected among the limited number of colors. Furthermore, there is also a case in which gradation is considered, in addition to the prediction accuracy. Colors constituting a patch set differ also depending on what type of design policy is employed.
As described above, it is difficult to simply determine colors that are to be included in a patch set. Thus, various proposals have been made as technologies for configuring patch sets. However, there is also a case in which a patch set is finally determined using intuition and experience of developers.
Generation of a patch set on the basis of experience of developers is limited. Furthermore, it is necessary to select and use a patch set with the knowledge of the degree of suitability of a patch set that has been generated in a certain manner for a corresponding apparatus or with the knowledge of which patch set among patch sets that have been generated in some manners is suitable for the apparatus. As a matter of course, although a reference patch set that is typically used may be used, there is no guarantee that the reference patch set is the most suitable patch set.